Antisocial personality disorder is a common condition in intravenous opioid abusers. More importantly, the diagnosis of antisocial disorder in opioid abusers is associated with a poor response to routine treatment, high rates of drug use (especially cocaine), high rates of aggressive and criminal behaviors, and high rates of HIV-1 infection. Efforts to improve the treatment outcome of this group is a major therapeutic challenge with compelling public health implications. We were funded approximately 48 months ago to do specific work in that area. The work included: 1) determining the prevalence of antisocial disorder in a previously unsurveyed population of opioid abusers; 2) examination of the diagnostic concordance rate for antisocial disorder using two structured interviews; 3) characterization of antisocial patients using dimensional measures of personality and psychopathy; and 4) evaluation of routine drug abuse treatment outcome and the efficacy of a novel behavioral intervention developed to reduce drug use and improve retention of these patients. Considerable progress has been made. Two studies are being proposed in the continuation project that will extend our work in this important area. We will complete a randomized, controlled clinical trial that is evaluating the efficacy of a highly structured behavioral intervention that utilizes a novel contingency contracting approach in treating antisocial opioid abusers. This new treatment intervention should be especially effective with these patients since it provides a motivating set of contingencies that specify exactly what behaviors are expected and provides timely reinforcements for those behaviors (e.g., reduced drug use). As noted above, that study is presently running. The new research also extends our work and that of others. The second study will focus on two relatively common dimensions of antisocial disorder - chronic aggressiveness and deficits in aversive reactivity (diminished ability to inhibit previously punished behaviors). The study will be conducted in a residential laboratory environment with opioid abusers who will be carefully selected to represent three distinct levels of antisocial behavior (low, mid, high) based on both diagnostic (DSM-III-R/DSM-IV) and dimensional assessment measures (e.g., Psychopathy Checklist-Revised; PCL- R). Both aggression and diminished aversive reactivity are features of antisocial disorder that possess important implications for future studies on diagnosis, etiology, and treatment of the disorder. To summarize, there are two major research components in this project (the clinical trial and the laboratory evaluation). They will provide valuable new information on both the characterization and treatment of antisocial disorder in opioid abusers. The first study will evaluate the efficacy of a novel behaviorally contingent approach to treatment aimed at reducing drug use and increasing treatment retention. The second study will provide new information on two behavioral domains important to the conceptualization of antisocial disorder--by establishing the utility of a novel procedure for behavioral indexing of aggressive tendencies in subgroups of opioid abusers with and without antisocial disorder, and through the psychophysiological assessment of aversive reactivity of these patients.